The present invention relates to a vacuum cleaner having a detection sensor for detecting an operation condition, i.e. an operational parameter, of the vacuum cleaner in a cleaner main body and a method for operating a vacuum cleaner.
The present invention relates to a vacuum cleaner and a method for operating the same, the vacuum cleaner comprising a detection sensor for detecting an operation condition in the vacuum cleaner having an electric driven blower and a control portion for controlling the electric driven blower in response to a detection value of the detection sensor.
In a conventional vacuum cleaner, for example shown in Japanese Patent Laid-Open (Kokai) No. Sho 61-280831, there has been known a technique that an output of an electric driven blower in a cleaner main body of the vacuum cleaner is controlled in accordance with a detection value of a pressure sensor, which detects an operation condition of the vacuum cleaner in the cleaner main body.
In the above stated vacuum cleaner, the vacuum cleaner comprises the pressure sensor for detecting the operation condition of the vacuum cleaner having the electric driven blower and a control portion for controlling the electric driven blower in response to the detection value of the pressure sensor.
In the above stated conventional vacuum cleaner, a method for decreasing an output of the electric driven blower at the operation range in a side of a large air flow amount, as the characteristic motion curve line shown in FIG. 2, or a method for decreasing the output of the electric driven blower at an operation range in a side of a small air flow amount, as the characteristic motion curve line shown in FIG. 3, can be attained.
However, in case of an attempt for an electric power saving or a noise reduction by decreasing the output of the electric driven blower at both the large air flow amount side and the small air flow amount side which are positioned respectively outside of the practical cleaner operation range, it is necessary to change over at a side of a directly-opposed characteristic as an algorithm.
However, it is difficult to attain with only one pressure sensor and it is necessary to make a combination of a plurality of pressure sensors or the different kinds pressure sensors, thereby it brings a defect that it becomes a complicated cleaner main body structure using a plurality of the pressure sensors.
Further, in case of a negative gradient control in regards to the characteristics of an air flow amount and a static pressure with respect to the electric driven blower, which is shown at A portion in the characteristic motion curve line in FIG. 4, it cannot adopt to in a practical use.
Because it causes a circulation control or a chattering phenomenon which comprises an increase in the static pressure over a change-over setting point (or a move toward the small air flow amount side), a lowering control for the output of the electric driven blower, a decrease in the static pressure below the change-over setting point, and a control for returning to a previous control condition.
In the conventional vacuum cleaner, in case of the output for decreasing in the electric driven blower, the return level and the change-over level have almost value. Also, the change-over level setting point and the new motion point go and return on the same load curve line. Accordingly, the chattering phenomenon occurs in the conventional vacuum cleaner.
Further, due to a method for detecting a pressure value, a control change-over point in case of the air flow amount varying from a large air flow amount side to a small air flow amount side differs to a return control change-over point in case of the air flow amount varying from the small air flow amount side to the large air flow amount side, namely a hysteresis phenomenon occurs, therefore it is difficult to carry out the control for the output in the electric driven blower with a high accuracy.
Namely, in the conventional method for operating the vacuum cleaner, in case of the output for increasing in the electric driven blower, unless it returns to a return point which becomes the same pressure value as that of the pressure value at the change-over level setting point, it does not return to the previous control condition. The air flow amount at the change-over level setting point in the forth passage differs to the air flow amount at the return point in the back passage, accordingly the hysteresis phenomenon occurs in the conventional vacuum cleaner.
Further, in the conventional vacuum cleaner, the electric driven blower generates a negative pressure according to a high speed rotation of a centrifugal fan by an electric motor and causes a suction force. In an aerodynamic characteristic of the electric driven blower in the cleaner main body as motion curve lines shown in FIG. 5, in case that it is driven by an electric motor having a series characteristic such as a commutator motor, since the load thereof becomes light at a small air flow amount side, a rotation number N rises, also a static pressure H rises. Besides, the consumption electric power W reduces.
Further, even when the electric driven blower is driven at a constant speed with a synchronous motor or an induction motor, as motion curve lines shown in FIG. 6, at the small air flow amount side it shows a similar tendency to that of FIG. 5, this tendency becomes remarkable in this case.
Namely, the above stated rotation number N is constant, an increase rate in the static pressure H reduces at the small air flow amount side, a decrease rate in a rotation torque becomes large, and a reduction in load becomes large. Accordingly, the decrease rates in the consumption electric power W and an electric current I become large.
In case of a variable speed operation by an inverter motor, etc., from a microscopic aspect, at each point of each of an operation condition, as motion curve lines shown in FIG. 7, it is shown with the combination of the constant speed control.
As motion curve lines shown in FIG. 8, by the operation of each portion (1), (2), (3) and (4) which is shown in the bold lines of a plurality of the constant speed characteristic motion curve lines, is changed over selectively, therefore the characteristic curve lines shown in FIG. 7 can be realized.
Now, a common point with the above stated various characteristics, as motion curve lines shown in FIG. 9, each rate of amounts .DELTA.H, .DELTA.N, .DELTA.W etc., which is respectively a variation amount of the static pressure H, the rotation number N, or the consumption electric power W with respect to the air flow variation amount .DELTA.Q differs to respectively at the large air flow amount side and also at the small air flow amount side.
When .DELTA.H/.DELTA.Q, .DELTA.N/.DELTA.Q, .DELTA.W/.DELTA.Q, and the combinations of those are detected using the pressure sensor, then a predetermined control for the vacuum cleaner can be carried out. In case that the detection sensitivity of the pressure sensor is made the same, it may carry out with an error judgment and an error control. However, in the conventional vacuum cleaner, no considerations are given to the variation rates and the control thereof.